1) Field of the Invention
The present invention relates to composite materials and, more particularly, relates to the consolidation of composite material by inductively heating the material and applying pressure thereto.
2) Description of Related Art
Composite materials typically include a fibrous material such as graphite that is interspersed in, or impregnated with, a matrix material. The fibrous material is generally strong and stiff and is held in place by the matrix material, which can be formed of a thermoplastic resin, a thermoset resin, or a metal. In combination, the fiber and matrix materials can provide a strong, stiff, lightweight material, which can also have dimensionally specific properties. Examples of composite materials include alumina-, boron-, or silicon carbide-based fibers provided in a weave, braid, or non-woven arrangement and combined with a matrix formed of Ultem® resin, a registered trademark of General Electric Company, or a metal such as titanium or aluminum.
Composite materials are consolidated during conventional manufacture by any of a number of methods such as vacuum hot pressing or hot isostatic pressing. These processes typically require long heat cycles due to the heating and cooling required for the tooling that is used to heat and consolidate the composite materials. The time and energy requirements result in high manufacture costs. U.S. Pat. No. 5,229,562 to Burnett, et al. and assigned to the assignee of the present invention, describes a manufacturing method for a composite workpiece in which an electrically conductive support is used to support the workpiece. The support is inductively heated, and thermal energy is conducted from the support to the workpiece. The mass and shape of the support can be controlled so that the workpiece can be heated evenly to a temperature sufficient for consolidation. However, the energy required to inductively heat the support adds to the manufacturing cost of the composite workpiece. In addition, temperature changes in the support can cause dimensional variations, thereby affecting the finished shape of the workpiece. Further, the time required for cooling the support between consolidation operations increases the manufacturing time for the workpieces.
Thus, there exists a need for an improved apparatus and method for consolidating a composite material. The apparatus and method should be capable of heating and cooling the composite material quickly to and from a temperature sufficient for consolidation. Preferably, the apparatus and method should not require that large support members are heated and cooled during each cycle.